Tuesday's jackpot is 2nd largest in U.S history

The Mega Millions jackpot in the U.S., now worth $586 million, is up for grabs on Tuesday and Canadians are welcome to test their luck south of the border in 45 jurisdictions where the lottery is offered. (Eric Risberg/Associated Press)

One of the largest lottery prizes in U.S. history is up for grabs on Tuesday, and Canadians are welcome to test their luck south of the border.

The Mega Millions jackpot has been boosted to $636 million, a jump from an earlier projection. It is the second largest jackpot in U.S history, trailing a $656-million prize last year.

Chuck Baumann, interim public affairs manager for Oregon Lottery, said Mega Millions are offered at 45 jurisdictions in the U.S.

"People get a little star-struck when the jackpot is huge," he told CBC News.

Regardless of where the winner comes from, however, the same U.S. federal withholding tax of 25 per cent applies, according to Baumann. The winner is also subjected to additional state taxes. In Oregon, for example, the withholding tax is eight per cent.

Paula Otto, executive director of the Virginia Lottery and Mega Millions' lead director, said ticket sales are ahead of projections, one of the primary factors pushing the jackpot higher.

She said the jackpot may be increased one more time on Tuesday morning in advance of the evening drawing.

"Lotto players are procrastinators. They tend to buy on the day of the draw," she told The Associated Press.

She said it's expected that between 65 and 75 per cent of the 259 million possible number combinations will be in play when the numbers are drawn.